Wrinkled Nanoporous Gold Films with Ultrahigh Surface-Enhanced Raman Scattering Enhancement
ABSTRACT Amplified by plasomonic nanostructured metals, Raman intensity of organic molecules and biomolecules can be dramatically improved, particularly at "hot spots" where intense electromagnetic fields are produced in the vicinity of narrow nanogaps between metallic nanostructures. Therefore, developing new substrates with a high density of "hot spots" has been the recent topic of intense study. Here we report wrinkled nanoporous gold films that contain abundant Raman-active nanogaps produced by deformation and fracture of nanowire-like gold ligaments. This novel nanostructure yields ultrahigh surface enhanced Raman scattering for molecule detection.
- SourceAvailable from: Yasushi Inouye
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- "However, their in-plane structural features and smooth ligament surfaces resulted from chemical etching constrain the local electromagnetic field strength below the limit for SERS-based single molecule detection212223. The SERS performances of nanoporous metal films can be further improved by introducing 3D quasi-periodic wrinkles through thermal contraction of pre-strained polymer substrates (Fig. 1a)242526. Using this procedure detailed in the Method section, rich SERS-active nanostructures at the ridges of the wrinkles, such as nanogaps and nanotips, are produced by deformation and failure of metal ligaments during film shrinking. "
ABSTRACT: Detecting and identifying single molecules are the ultimate goal of analytic sensitivity. Single molecule detection by surface-enhanced Raman scattering (SM-SERS) depends predominantly on SERS-active metal substrates that are usually colloidal silver fractal clusters. However, the high chemical reactivity of silver and the low reproducibility of its complicated synthesis with fractal clusters have been serious obstacles to practical applications of SERS, particularly for probing single biomolecules in extensive physiological environments. Here we report a large-scale, free standing and chemically stable SERS substrate for both resonant and nonresonant single molecule detection. Our robust substrate is made from wrinkled nanoporous Au₇₉Ag₂₁ films that contain a high number of electromagnetic "hot spots" with a local SERS enhancement larger than 10⁹. This biocompatible gold-based SERS substrate with superior reproducibility, excellent chemical stability and facile synthesis promises to be an ideal candidate for a wide range of applications in life science and environment protection.Scientific Reports 10/2011; 1:112. DOI:10.1038/srep00112 · 5.58 Impact Factor
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ABSTRACT: Nanoporous gold films containing various amounts of residual silver have been synthesized by controllable dealloying and subsequent annealing for surface-enhanced Raman scattering (SERS). It was found that the residual Ag plays an important role in the SERS effect of dealloyed nanoporous gold. More residual Ag gives rise to better SERS effects when nanopore sizes are nearly identical. Moreover, homogenization of the residual silver by annealing can further improve the SERS enhancement of nanoporous Au–Ag alloys.The Journal of Physical Chemistry C 09/2011; DOI:10.1021/jp205892n · 4.77 Impact Factor
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ABSTRACT: Due to its demonstrated usefulness in fields such as trace analysis, biodiagnosis, and in vivo study, surface-enhanced Raman scattering (SERS) has received renewed interest in recent years. Development of SERS substrates is of great importance as the SERS intensity and reproducibility depend strongly on the SERS substrates. In this paper we report the fabrication of Au nanoporous film (NPFs) by self-organization of networked ultrathin Au nanowires for use as SERS substrates. The acquired Au NPFs display controllable thickness, low relative density, and considerable specific surface area. Furthermore, this self-organization of nanowires not only provides abundant junctions between nanowires, 5-20 nm nanopores, and three-dimensional nanowells, but also makes nanopores/nanogaps down to 1-2 nm. These nanoscale characteristics result in a high spatial density of hotspots with Raman enhancement factors up to 10(9). Combined with the uniformity and high purity, our Au NPF provides high-quality substrates for SERS sensing.Analytical Chemistry 12/2011; 83(23):9131-7. DOI:10.1021/ac2022647 · 5.64 Impact Factor